My student Abhinav Aggarwal has just written the inaugural post on his new blog (the name of which, I hope, is not a comment on the soporific qualities of my advisement 🙂 His first post is on the Clever algorithm by Jon Kleinberg. This is inarguably, the paper that started the modern, spectral-based approach to web search that Google has built on so successfully.

Some questions worth pondering while reading through Abhinav’s summary (and hopefully also the seminal paper itself): 1) Why did PageRank “beat out” the Clever algorithm in real-world web search? 2) Are there domains besides web search where one might use a “top left and right eigenvector” approach like the Clever algorithm? 3) What about the “soft” results in the paper like the use of the second eigenvector for clustering? Can these be formalized in an interesting way?

Congratulations to Mahdi Zamani who just passed with distinction his
dissertation defense on “Scalable and Robust Algorithms for Privacy-Preserving Applications”. After graduation, Mahdi will be will be moving to Yale CS as a Postdoc to work with Joan Feigenbaum and Bryan Ford on the Dissent Project. Serving on his dissertation committee were Jed Crandall, Trilce Estrada and Brian Ford(EPFL).

It’s a great pleasure to have worked with Mahdi and he’ll really be missed in both our own research group and at UNM.

Congratulations to Dr. George Saad who just defended his dissertation (with distinction) yesterday on “Selfishness and Malice in Distributed Systems”. George’s dissertation focused on designing 1) algorithms for self-healing in networks with Byzantine nodes and 2) designing mediators to improve social welfare in a type of El-Farol game with both positive and negative networks effects. Here are slides from his excellent talk.

This is a neat result in the dynamic graph setting where an adversary can add and delete edges in a graph, but the number of nodes is always fixed at n. One of their results is as follows. In the case where the maximum number of rounds that it takes a message to traverse the network is always polylog, they give a polylog time algorithm that allows each node to approximate within a constant factor the densest subgraph. This is in the CONGEST model where in each round, each node can send an O(log n) bit message to each neighbor.

Usually on this blog, I allow only a 1 slide dissertation summary, but today I’m making an exception for 2 slides (at least they have the same x-axis :). The slides below summarize the performance of 4 Byzantine agreement algorithms. The CKS algorithm is from the paper “Random oracles in Constantinople: Practical asynchronous Byzantine agreement using cryptography“. The remaining 3 algorithms are from M’s dissertation, and the algorithms with the RB prefix assume the existence of a random beacon.

Congratulations to Dr. Maxwell Young who successfully defended his dissertation on Resource-Efficient Communication in the Presence of Adversaries at the University of Waterloo yesterday. Max got his Masters degree with me at UNM way back when I first started as a faculty member, and he was the very first student with whom I published a paper. He’s hard-working, talented, and also a lot of fun to work with. One of the great pleasures of academia is seeing student develop as researchers, and then have the possibility to continue to work with them as colleagues. Max and I have been actively working together for many years now, and I’m looking forward to visiting him in Singapore during his post doc with Seth Gilbert next year.